A graphical user interface (GUI) may include multiple elements that can receive input. The target of the input is said to have focus, and elements eligible for focus within a document are called focusable elements. In a GUI, input that is received is processed according to an element that currently has focus. For example, if a GUI contains two editable text boxes, when a user enters text through a keyboard, the text is rendered in the text box that currently has focus.
In a GUI that receives input from a pointing device, such as a mouse, the currently focused element is determined based on the location of a cursor or pointer when a user submits a select command (e.g., clicks a mouse button). If the cursor or pointer is over a text box when the user clicks the mouse button, then that text box is given focus and future input, such as through a keyboard, is directed to the text box until the focus is moved to another element.
In a GUI that receives input from devices without pointing mechanisms, such as keyboards or remote controls, an alternative mechanism is implemented to allow a user to specify an element to be given focus, and thus, the target of keyboard (or other device) input.
Browser or other rendering engine applications that provide a mechanism for displaying documents that include focusable elements (e.g., hypertext markup language (HTML) documents, dynamic HTML documents, or web pages) are implemented to support navigation between focusable elements in a document by way of a mouse or other similar pointing device. Some such documents also support navigation through the focusable elements of the document according to a tab order that defines a sequential order that determines which element is focused next when a user presses a tab key.
Recently introduced technology allows web pages (and potentially other types of documents that may include focusable elements) to be rendered using devices other than computers. These other devices may include, but are not limited to, a television set, a cellular phone display, and a multi-modal device, such as the NOKIA 9110 Communicator. Such devices do not typically include a pointer input device, such as a mouse.
Rendering engines implemented on such devices may be programmed to receive an input that behaves like the press of a tab key to allow a user to move sequentially from one focusable element in a document to another. However, cascading style sheets, dynamic HTML, and the like support dynamic rendering of documents in such a way that the visual layout of a rendered document may differ from the layout that was intended when the document was generated and possibly, when the tab order of focusable elements in the document was established. Accordingly, moving from one focusable element to another either sequentially or based on an established tab order may not result in visually logical focus navigation, and it is desirable for a rendering engine to support directional focus navigation based on directional inputs, such as an arrow key press.